The use of environmentally beneficial compositions, especially those that are referred to as “green”, is important in choosing biocidal materials that can be used as preservatives. The use of natural or naturally-derived materials is also very much of interest in ingested compositions. It is also important that both green and naturally-derived materials be utilized in a composition that will provide antimicrobial, antibacterial, antifungal, and antiviral properties as well as preservative capability. If all of the components of a biocidal composition are GRAS (Generally Regarded as Safe) and are approved for food use, the resulting composition could also be ingested with little or no side effects.
Although Nα-(C1-C22) alkanoyl di-basic amino acid alkyl (C1-C22) ester salts have been known since the 1960's, one of the first patents to recommend these amino acids, specifically for food applications was U.S. Pat. No. 3,825,560 (issued Jul. 23, 1979). A number of derivatives are disclosed including Nα-cocoyl-L-arginine ethyl ester pyrrolidone carboxylate and Nα-lauroyl-L-arginine methyl ester hydrochloride. Since this publication there have been several more patents issued or published disclosing specifically Nα-lauroyl-L-arginine ethyl ester hydrochloride salt (“LAE”). These include U.S. Pat. No. 5,780,658 that discloses a process to prepare LAE, as well as disclosing its use for food applications. U.S. Pat. No. 7,074,447 B2 discloses an antimicrobial composition comprising LAE with potassium sorbate. U.S. Pat. No. 7,087,769 is another process patent suggesting its use for food. Two patent publications, U.S. 2004/0166082 and U.S. 2004/0175350, disclosure di basic amino acid alkyl ester salts useful for cosmetic applications. U.S. 2004/0254232 covers oral care while U.S. 2004/0265443 covers food. U.S. 2005/0175747 discloses complexes formed between LAE and various anionic hydrocolloids. All of the above references are incorporated into the body of our present invention.
One of the purposes of this invention is to utilize a synergistic mixture of Nα-long chain alkanoyl di basic amino acid alkyl ester salt type biocide that will increase the preservative performance compared to the sole use of Nα-long chain alkanoyl di basic amino acid alkyl ester salts. By combining glycerol esters of fatty acids, with chain lengths of from C6 to C14 with Nα-long chain alkanoyl di basic amino acid alkyl ester salts, a significant broadening of cidal activity is achieved. Furthermore, this synergistic mixture allows the use of much lower levels of either biocide while maintaining biocidal efficacy and thereby reduces cost.
The literature is replete with numerous references concerning glycerol monofatty acid esters having antiviral and antibacterial activity. The most active monoglycerides consist of those esters formed from saturated fatty acids having from 6 to 14 carbon atoms. U.S. Pat. No. 4,997,851 teaches the use of saturated fatty acids and glycerol monofatty acid esters as effective antiviral agents against the HIV and HSV-1 viruses. They were also active against a variety of gram positive and gram-negative bacteria.
U.S. Pat. No. 5,434,182 discloses the spermicidal, antimicrobial and cytocidal activity of glycerol monofatty acid esters. It discloses the combination of fatty acyl glycerides, a chelating acid, and a surfactant, which confer excellent antimicrobial activity for preserving processed meats and for disinfecting poultry carcasses. When only one of these three agents was used, the anti-microbial performance was considerably reduced. U.S. Pat. No. 6,414,023 B1 discloses the use of fatty acid monoglycerides in conjunction with 2,4-dichlorobenzyl alcohol.
John J. Kabara in U.S. Pat. No. 6,638,978 B1 lists a preservative formulation for food and cosmetics consisting of monolaurin (ML), caprylic and capric acid mixture, and propylene glycol in an aqueous base. U.S. 2005/0084471 A1 teaches the preparation of a preservative for meat, fruits, and vegetables and for the disinfection of inanimate surfaces. The actives include a propylene glycol C7-C14 fatty acid ester as the major component, a surfactant, and an enhancer. Enhancers include phenolic antioxidants and/or a paraben ester. Lastly, U.S. Patent 2006/0030512 A1 describes a long lasting anti-microbial film comprising a glycerol monoester, an amphoteric surfactant, a chelating agent and a solvent like propyl alcohol plus other incipients. All of the above references are incorporated into the body of our present invention.